Telephone traffic indicating apparatus



June 10, 1947. E. w. HILL TELEPHONE TRAFFIC INDICATING APPARATUS Filed Dec. 22, 1944 IN VEN'TOR E W, ELM

A TTORNE Y Patente-d June 10, 1947 TELEPHONE TRAFFIC INDICATING APPARATUS' Edward Weathers Hill, Takoma Park, Md., as-

signor to American Telephone'and Telegraph Company, a corporation of Newv Yorku Application December 22, 1944, Serial No. 569,314

6 Claims.

This invention relates to telephone systems and, more particularly, to apparatus for measuring or observing trallc in telephone ollices.

In the panel type of telephone system, for example, a calling subscribers telephone set may be connected toY a called subscribers telephone set usually under the control of a sender and a decoder located at the calling subscribers central oiice, In general, the decoder serves to select the cnice trunk (or oice trunks) over which the call is to be completed to the called party. After the calling partys set is connected to a sender and the called number dialed, a decoder is then seized by the sender to perform the function just stated. Thereafter the sender retains control of the switching apparatus until the called subscribers line is reached.. The decoder is released by the sender immediately after its trunk selecting function has been completed and, as often happens, the decoder will also be released when it is found to be busy or in trouble.

The decoder is a complex apparatus and quite expensive. There are generally many fewer decoders than senders, the ratio being something like seventy to one. It is important, therefore, to determine how many of the decoders in any central office are busy at any instant or during any brief interval of time, such as five seconds, or ten seconds, etc., during a period, for example, when traffic through the central oflice may be heavy.

It is one of the objects of this invention to provide a simple and relatively inexpensive arrangement for measuring or observing the rate at which the decoders (or other devices) of the central oice are operated within a predetermined time interval. This object may be accomplished by connecting` a voltmeter through a timing or discharge control circuit of resistance and capacitance to a plurality of condensers each of which is associated with one of the decoders. l.

Each condenser is normally charged to a predetermined voltage and when the associated decoder is seized, the corresponding condenser will be connected to the voltmeter through the timing or discharge control circuit. The deilection of the voltmeter may serve to indicate the rate at which decoders are operated within any predetermined time interval.

This invention will be better understood from the more detailed description hereinafter following when read in connection with the accompanying drawing illustrating one embodiment of the invention given merely for illustrative purposes.

Referring to the drawing, the dial telephone subscriber-s set DS is shown connected to the line finder LF, the tip, ring and sleeve terminals of which may be connected through a selector SC to a sender SDi. The called subscribers number is dialed by the calling partys telephone set DS in the usual way and the dialed number is registered by the sender SD1. The sender SD1 is then connected by a connector switch CN to a decoder DC1 which serves to route the call to the proper oilice or oiiices, after which the decoder DC1 will be disconnected from the sender SD1, but the sender S131 will operate the switches (not shown) which are required to complete the connection of the calling'partys set DS to the called partys set (not shown). The decoder DC1 is similar to decoder DC2 and to other decoders to which any sender such as SD1 may have access. The decoders DC1, DCz, etc., and the other apparatus above referred to are of well-known type and are present in the usual panel dial central oiice.

As soon as the decoder DC`1 is seized by the sender SD1, a relay such as DR1 will become operated to supply ground to the sleeve terminal S of the decoder DC1 so as to make it appear busy to other senders that may seek access t0 it at the time when it is routing a call for sender SD1. The ground placedon the armature of relay DH1 will cause relay B1 of apparatus RA1 to become operated over a path including the make contact and armature of relay DH1, the make-beforebreak contact'of relay A1, the winding of relay B1, battery V1, and ground. The operation of relay B1 causes relay A1 to operate, the operating path for which includes battery V1, the lower or operating Winding of relay A1, the lower make contact and armature of relay B1, the make-before-break Contact of relay A1, the armature and make contact of relay DB1 and ground. Relay A1 is then locked in its operated position, the locking path including battery V1, the upper or locking winding of relay A1, the armature and make contact of relay A1, the armature and make contact of relay DH1 and ground. Relay A1 will remain locked in its operated position as long as the decoder is busy. Moreover, relay B1 will be released immediately after relay A1 becomes operated by virtue of the opening of the operating path of relay B1 at the make-before-break contact of relay A1.

It is to be observed that while relay B1 is released, battery Vz will be connected to condenser C1 over a path completed through the upper back contact and armature of relay B1 and resistor R1. Condenser C1 is thus normally charged to the voltage of battery'Vz. However, as soon as relay B1 becomes operated, the condenser C1 is connected to the voltmeter VM over a path comprising condenser C1, resistor R1, the upper armature and make contact of relay B1, resistor R2, voltmeter VM and ground. Condensers Cz and C1 are bridged between opposite terminals of resistor R2 and ground, as shown, and hence these condensers become charged immediately upon their connection to condenser C1. As relay B1 is operated only momentarily, the high voltage to which condenser C1 is normally charged by battery V2 will be transferred momentarily to condensers C2 and C3 and at the same time the pointer of the voltmeter VM will be deflected. The deilection of the pointer of meter VM Will be reduced as the charges on condensers C2 and C3 become lowered and the deilecticn will be zero in due course.

The decoder DCz is shown connected through relay apparatus RAz-which is similar to relay apparatus BA1-to resistor R2 and its bridging condensers C2 and C3 and then to the voltmeter VM. As decoders DC1, DCz, etc., may be seized in rapid succession during periods of heavy traiic, the condenser such as C1 of apparatus BA1 and the corresponding condensers of the other apparatus RAZ, etc., which are fully charged, will be successfully connected to the measuring instrument VM through the common resistor R2 and its bridging condensers C2 and C3. The charges on condensers C2 and C3 will be rapidly replenished during the interval when decoders are rapidly seized and the pointerof meter VM will be held, within certain limits, at or near this maximum deflection. The attendant may therefore quickly observe whether the call rate is peaking up in the central oiice.

The meter VM may be of any type of recording or non-recording voltmeter. The recording type of voltmeter would be employed whenever permanent records of service conditions are required.

Whenever only one decoder such as DC1 is seized Within any predetermined time interval, such as five seconds, or ten seconds, or 60 seconds, etc., the deection of the voltmeter will reach a certain relatively high value and drop to successively lower values at a predetermined rate. Should other decoders be seized, either at regular periods or irregular periods thereafter, the voltmeter deflection will be temporarily increased each time a decoder is seized and thus the average indication over a given period will be higher. The rate of change of the voltmeter indications will be determined by the constants of the circuit connected to the voltmeter VM. The rate of discharge through the voltmeter may be changed, for example, by modifying the magnitude of resistor R2 or of the condensers C2 and C3. The voltmeter VM will serve to integrate the calling rate, i. e., the rate at which decoders are seized in the central ofce.

The invention has been shown and described as applied to apparatus for determining the calling rate of decoders in a panel type automatic telephone central oice. The invention is equally applicable to observe the calling rate of senders, markers, and other equipment of any type of dial central oiiice. The invention is in general applicable to any electrical 01 mechanical apparatus employing a plurality of translating devices that may be operated intermittently.

While this invention has been shown and described in certain particular embodiments merely for illustrative purposes, it will be understood that it is equally applicable to other and widely varied organizations without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is:

l. Traic indicating apparatus for roughly registering the number of translating devices that have operated in a brief time interval, comprising a plurality of normally charged condensers each corresponding to and controlled by one of said devices, a common discharge circuit having resistance and capacitance of predetermined magnitudes, a measuring element connected to said discharge circuit, and means for operating said devices and transiently connecting the corresponding condensers controlled by said devices to said discharge circuit immediately upon the operation of said devices.

2. Traiiic measuring apparatus for registering the approximate number of independent translating devices operated within a brief time interval, comprising a plurality of equal condensers each associated with one of said devices, means for normally charging all of said condensers to a predetermined voltage, a discharge control circuit having resistance and capacitance, a meter connected to said control circuit, and means responsive to the operation of each translating device to momentarily connect the associated condenser to said control circuit immediately upon the operation of said translating device.

3. Telephone traic measuring apparatus for a central office having a plurality of independent decoders, comprising a plurality of normally charged condensers each controlled by one of said decoders, a discharge control circuit having predetermined resistance and capacitance, a recording meter connected to said discharge control circuit, and means controlled by each decoder to transiently connect its associated condenser to said discharge control circuit immediately upon the operation of said decoder.

4. The combination of a plurality of independent, intermittently operated devices, a plurality of sources of voltage each associated with one of said devices, a timing circuit comprising a, series resistor 'and shunt condenser, a voltmeter connected in series With said resistor, and means responsive to each operated device to immediately connect its associated source of voltage to said timing circuit, whereby said voltmeter will indicate the approximate number of said devices that have become operated in a predetermined time interval.

5. The combination of a plurality of independent devices that are operated intermittently, a timing' circuit comprising a resistor and condenser in shunt therewith, a voltmeter connected to said timing circuit, a plurality of condensers each individual to one of said devices and normally charged to a predetermined voltage, and means controlled by each device for momentarily connecting the condenser individual thereto to said timing circuit immediately upon the operation of said device, whereby said voltmeter will be deflected in proportion to the approximate number of said devices operated in a predetermined time interval.

6. Apparatus for registering the approximate number of independent devices operated within a brief time interval, comprising a plurality of normally charged condensers one corresponding to each of said devices, a timing circuit of resistance and capacitance, a meter connected to said timing circuit, and means responsive to the operation of any of said devices to imme- 5 diately connect the condensers corresponding to the operated devices momentarily to said timing circuit.

EDWARD WEA'IHERS HILL.

REFERENCES CITED Number UNITED STATES PATENTS Name Date Humphries Mar. 19, 1940 Longer et al Apr. 4, 1939 Gaarz et a1 June 9, 1931 Lenehan July 7, 1931 

